For a number of years, cargo ships have been carrying their loads in large rectangular boxes called containers. These containers are constructed of a framework of steel or the like and are also strengthened so as to withstand pressures created by stacking one container upon the other and by various forces which are encountered at sea. Although these containers come in various sizes, the more standard size is substantially the same as a large truck van.
Containers are loaded and unloaded and moved about by cranes. A spreader bar suspended by the crane engages eyes which exist in the corner castings on the containers. The crane raises the spreader bar to hoist the container aloft and move it to its desired location.
It is common practice to stack containers vertically and horizontally to form rows. In order to join and lock the upper corners of adjacent containers so as to prevent accidental slippage, devices called stacking pads are used. These stacking pads are placed for locking and unlocking by workmen or "lashers" who move across the top of the stacks.
While the safety of the workmen has always been a great concern, recent government restrictions and rules require that some type of safety device be provided for protection of the lashers. Various devices have been proposed, including the use of a safety cage which is hoisted atop a stack of interlockable cargo containers and which allows the lashers to operate within the cage and still have access to the locks. Such a cage is shown and described in U.S. Pat. No. 4,705,140, issued Nov. 10, 1987. The cage includes a reel tether hanging from a trolley which rolls along the athwartship extensions of a roof boom and hooks onto a worker's safety harness to enable him to leave the cage.
While this cage provides safety, it is also cumbersome and obviously requires considerable expense to equip a terminal with the necessary number of cages.
The present invention provides a means for rotatably connecting a retractable lifeline block to a corner casting of the frame for the container or to a similar casting which might be mounted on a crane working to load and unload the containers. Such a device allows each worker to have a self-contained unit for attaching between his harness and to the casting so as to provide individual protection while still providing an economical apparatus for providing such a function.